We propose a surface-mounted MEMS-based health monitoring system. Since MEMS sensors are pervasive but not invasive, they can be deployed in very dense arrays over the whole structure, without affecting its dynamics. With reference to a standard double cantilever beam test, we show experimental results relevant to a very simple set-up, featuring a three-axis, digital output commercial off-the-shelf MEMS accelerometer held fixed to the specimen. While sensitivity (around 1,000 LSb/ g) proved sufficient for monitoring applications, instrumental noise had to be checked to understand whether the sensor can effectively recognize the delamination length. Owing to the capability of the MEMS to detect its own orientation with respect to the vertical direction (being sensible to the gravity acceleration as well), we converted the acceleration into a measure of the rotation (or deformation) of the specimen. To filter out the high-frequency oscillations displayed by the acceleration record, we moved to the frequency regime: keeping the amplitude of the Fourier transform at the driving frequency, normalized by the average displacement in a cycle, a high sensitivity to the length of the growing delamination is obtained. This result is shown to be in good agreement with a theoretical beam-bending model of the specimen response.